Twisted fiber microfluidics: a cutting-edge approach to 3D spiral devices.

The development of 3D spiral microfluidics has opened new avenues for leveraging inertial focusing to analyze small fluid volumes, thereby advancing research across chemical, physical, and biological disciplines. While traditional straight microchannels rely solely on inertial lift forces, the novel spiral geometry generates Dean drag forces, eliminating the necessity for external fields in fluid manipulation. Nevertheless, fabricating 3D spiral microfluidics remains a labor-intensive and costly endeavor, hindering its widespread adoption. Moreover, conventional lithographic methods primarily yield 2D planar devices, thereby limiting the selection of materials and geometrical configurations. To address these challenges, this work introduces a streamlined fabrication method for 3D spiral microfluidic devices, employing rotational force within a miniaturized thermal drawing process, termed as mini-rTDP. This innovation allows for rapid prototyping of twisted fiber-based microfluidics featuring versatility in material selection and heightened geometric intricacy. To validate the performance of these devices, we combined computational modeling with microtomographic particle image velocimetry (µTPIV) to comprehensively characterize the 3D flow dynamics. Our results corroborate the presence of a steady secondary flow, underscoring the effectiveness of our approach. Our 3D spiral microfluidics platform paves the way for exploring intricate microflow dynamics, with promising applications in areas such as drug delivery, diagnostics, and lab-on-a-chip systems.

Optimization and Fabrication of Multi-Level Microchannels for Long-Term Imaging of Bacterial Growth and Expansion.

Bacteria are unicellular organisms whose length is usually around a few micrometers. Advances in microfabrication techniques have enabled the design and implementation of microdevices to confine and observe bacterial colony growth. Microstructures hosting the bacteria and microchannels for nutrient perfusion usually require separate microfabrication procedures due to different feature size requirements. This fact increases the complexity of device integration and assembly process. Furthermore, long-term imaging of bacterial dynamics over tens of hours requires stability in the microscope focusing mechanism to ensure less than one-micron drift in the focal axis. In this work, we design and fabricate an integrated multi-level, hydrodynamically-optimized microfluidic chip to study long-term Escherichia coli population dynamics in confined microchannels. Reliable long-term microscopy imaging and analysis has been limited by focus drifting and ghost effect, probably caused by the shear viscosity changes of aging microscopy immersion oil. By selecting a microscopy immersion oil with the most stable viscosity, we demonstrate successful captures of focally stable time-lapse bacterial images for ≥72 h. Our fabrication and imaging methodology should be applicable to other single-cell studies requiring long-term imaging.

Intracellular Nanomaterial Delivery via Spiral Hydroporation.

In recent nanobiotechnology developments, a wide variety of functional nanomaterials and engineered biomolecules have been created, and these have numerous applications in cell biology. For these nanomaterials to fulfill their promises completely, they must be able to reach their biological targets at the subcellular level and with a high level of specificity. Traditionally, either nanocarrier- or membrane disruption-based method has been used to deliver nanomaterials inside cells; however, these methods are suboptimal due to their toxicity, inconsistent delivery, and low throughput, and they are also labor intensive and time-consuming, highlighting the need for development of a next-generation, intracellular delivery system. This study reports on the development of an intracellular nanomaterial delivery platform, based on unexpected cell-deformation phenomena via spiral vortex and vortex breakdown exerted in the cross- and T-junctions at moderate Reynolds numbers. These vortex-induced cell deformation and sequential restoration processes open cell membranes transiently, allowing effective and robust intracellular delivery of nanomaterials in a single step without the aid of carriers or external apparatus. By using the platform described here (termed spiral hydroporator), we demonstrate the delivery of different nanomaterials, including gold nanoparticles (200 nm diameter), functional mesoporous silica nanoparticles (150 nm diameter), dextran (hydrodynamic diameters between 2-55 nm), and mRNA, into different cell types. We demonstrate here that the system is highly efficient (up to 96.5%) with high throughput (up to 1 × 106 cells/min) and rapid delivery (∼1 min) while maintaining high levels of cell viability (up to 94%).

Commotio cordis, therapeutic hypothermia, and evacuation from a United States military base in Iraq.

BACKGROUND: Therapeutic hypothermia (TH) has been demonstrated to improve clinical outcomes after out-of-hospital ventricular fibrillation (VF) cardiac arrest. It remains unclear if TH can be safely and effectively used in the setting of traumatic arrest. Furthermore, the use of TH methods in the pre-hospital and transport environments remain poorly established and a domain of active investigation. OBJECTIVES: To describe a case of successful TH utilization after blunt trauma with commotio cordis and pulmonary contusion, and to describe the continuation of TH during international fixed-wing aeromedical transport. CASE REPORT: A 33-year-old active duty soldier suffered blunt chest trauma and immediate VF arrest. He was successfully resuscitated with cardiopulmonary resuscitation and defibrillation attempts. Given his ensuing comatose post-arrest state, he was therapeutically cooled and subsequently evacuated from Iraq to Germany, with cooling maintenance established in flight without the availability of training or commercial cooling equipment. The patient exhibited an eventual excellent neurologic recovery. To utilize TH for this patient, military physicians with limited local resources employed a telemedical approach to obtain a hypothermia protocol to develop a successful treatment plan. CONCLUSIONS: The patient's successful resuscitation suggests that care should not be withheld for blunt trauma patients without vital signs in the field if VF is present, until the differential diagnosis of commotio cordis has been considered.

Impact of perioperative cardiac assessment guidelines on management of orthopedic surgery patients.

PURPOSE: The study assessed whether the American College of Cardiology/American Heart Association (ACC/AHA) preoperative cardiac assessment guidelines impact patient management and predict major cardiac events in patients undergoing orthopedic surgery. SUBJECTS AND METHODS: We conducted a retrospective review of 338 consecutive orthopedic preoperative evaluations performed by internal medicine consultants. Major cardiac events were defined as myocardial infarction, congestive heart failure, and sudden cardiac death. RESULTS: Major cardiac events occurred in 5.7% of patients. Patients with minor or absent ACC/AHA clinical risk predictors were less likely to have major cardiac events (P = .007). More than half (51%) of patients meeting ACC/AHA indications for noninvasive cardiac tests did not receive them. However, most (69%) major cardiac events occurred in patients not meeting criteria for cardiac testing. Abnormal noninvasive cardiac testing results did not alter medication recommendations and only resulted in coronary revascularization in 0.6% of patients. Only 3% of patients with abnormal noninvasive cardiac testing results had major cardiac events. Patients with abnormal cardiac test results were more likely to have recommendations for perioperative beta-blockade (P <.01). Patients aged more than 70 years (odds ratio 5.0; 95% confidence interval, 1.32-19.28) and patients undergoing hip surgery (odds ratio 7.5, 95% confidence interval, 1.02-54.55) were more likely to have major cardiac events. Major cardiac events occurred in 12% of urgent and 4% of elective procedures (P = .009). CONCLUSIONS: The ACC/AHA guidelines accurately predict cardiac risk in orthopedic surgery. Abnormal noninvasive cardiac test results rarely affected preoperative recommendations, but improved compliance with beta-blocker therapy. Advanced age, urgent procedures, and hip surgery were associated with increased risk of major cardiac events.

Clinical value of carotid intima-media thickness testing.

Carotid intima-media thickness (CIMT) testing is recognized as a valid method for the noninvasive assessment of atherosclerosis. In addition to its association with known cardiovascular risk factors and both prevalent and incident coronary heart disease, the rate of CIMT progression is directly related to the risk for future cardiovascular events. Subsequently, CIMT has been a valuable research tool in clinical trials in the assessment of therapeutic agents directed against atherosclerosis. An overview of CIMT testing including its precise measurement, establishment as a surrogate for atherosclerosis by epidemiologic trials, role in clinical trials, and potential applications in both primary and secondary coronary heart disease prevention is presented.

Beaver fever arthritis.

Giardia lamblia, a flagellated protozoan and common cause of gastroenteritis, is a rare but previously reported cause of reactive arthritis (ReA). We report a case of inflammatory oligoarthritis in a young woman after infection with Giardia. Two weeks after being treated, she developed an inflammatory arthritis of her left knee and right elbow that was refractory to nonsteroidal antiinflammatory medication. Antinuclear antibody, rheumatoid factor, and HLA-B27 tests were negative. She had almost immediate relief with intraarticular injection of corticosteroids. We review the previously reported cases of ReA following giardiasis and discuss possible pathogenic mechanisms. Although ReA most commonly occurs after chlamydial urethritis or gastroenteritis associated with typical enteropathic bacteria, important historical clues could point to less common pathogens such as Giardia. Physicians should be aware of these less common causes of ReA, because this could have important diagnostic and therapeutic implications.